How to build blender with Outliner Branch (or any other branch)?
In order to build the outliner branch you switch to that branch first.

git checkout soc-2019-outliner


Make sure that the branch is up-to-date:

git pull


Then you're ready to build.

make full


When you want to switch back to the master branch the command is:

git checkout master


Unfortunately you can't directly apply the OptiX patch to the outliner branch because of incompatible code changes that cause merge conflict.